There is a motor constructed such that a stator is formed by winding a coil around a stator core, and electric current supply to the coil is controlled, thereby rotating a rotor. In such a motor, it is commonly known that if the stator core is skewed, then uneven rotation of the rotor can be prevented.
Here, if the stator core is constructed to be splittable, the space factor of the coil winding can be improved, as a coil can be wound for each of the split laminated core segments. In the laminated core segment, a convex section for engagement is provided on one end section in the circumferential direction, and a concave section for engagement is provided on the other end section. When manufacturing the rotor, punched core segments are laminated while they are skewed, to manufacture the laminated core segment. After winding the coil, the laminated core segments are connected to the convex section and the concave section for engagement in the circumferential direction so as to form a circular shape. Furthermore, if connection sections are welded, the laminated core segments become a ring-shaped stator core (for example, refer to Patent Document 1).
On the other hand, conventionally, in rotary electric machines such as brushless motors, a stator side core in which magnetic steel plates punched in a substantially ring shape by presswork are laminated, is used. Among these rotary electric machines, in an inner rotor type brushless motor or the like, teeth sections on which coils are wound are formed on the inner circumference side of a core. However, at this time, if a stator core formed by laminating ring-shaped steel plates is used, the coils cannot be easily wound around the teeth sections that are provided so as to project in the inner circumferential direction. For this reason, in the inner rotor type rotary electric machine, the stator core is cut along the rotation shaft line to radially split it to form split core units, as disclosed in Patent Document 2. After that, the coil is wound for each of the split core units to make a plurality of stator segments, and these stator segments are assembled in a ring shape to form the stator.
FIG. 22 is a perspective view showing a construction of a stator segment 251. A plurality of the stator segments 251 is installed in the circumferential direction, thereby forming a stator 252 in a shape shown in outline by the chain line. The stator segment 251 is constructed such that a synthetic resin insulator 254 is attached to a split core unit (laminated core segment) 253 shown in FIG. 23, and a coil 255 is wound thereon. As shown in FIG. 24, the split core unit 253 is formed such that core pieces 257 formed by punching out from a magnetic steel plate 256 by pressing, are laminated. The core pieces 257 are laminated while displacing each one by a predetermined angle from the one before it, and the stator segment 251 is formed so as to have a shape slightly tilted with respect to the axial direction as shown in FIG. 22. The insulator 254 is mounted on the split core unit 253, and then a winding wire 258 is wound so as to form the coil 255. A plurality of the stator segments 251 is installed in the circumferential direction, forming the cylindrical stator 252. At this time, as a result of the inclination of the stator segments 251, a skew 259 is formed for preventing operating vibration and noise in the stator 252.    [Patent Document 1] Japanese Unexamined Patent Application, First Publication No. 2005-278298    [Patent Document 2] Japanese Unexamined Patent Application, First Publication No. 2003-304655    [Patent Document 3] Japanese Unexamined Patent Application, First Publication No. 2003-284269    [Patent Document 4] Japanese Unexamined Patent Application, First Publication No. 2001-300647    [Patent Document 5] Japanese Unexamined Patent Application, First Publication No. Hei 10-75552